<template>
  <div class="type-nav">
    <div class="container">
      <div @mouseleave="leaveShow" @mouseenter="enterShow">
        <h2 class="all">全部商品分类</h2>
        <!-- 三级联动 -->
        <!-- 过渡动画 -->
        <transition name="sort">
          <div class="sort" v-show="show">
            <!-- 事件委派 -->
            <div class="all-sort-list2" @click="goSearch">
              <div
                class="item"
                v-for="(c1,index) in categoryList"
                :key="c1.categoryId"
                :class="{cur:currentIndex == index}"
              >
                <h3 @mouseenter="changeIndex(index)">
                  <a
                    :data-categoryName="c1.categoryName"
                    :data-category1Id="c1.categoryId"
                  >{{ c1.categoryName }}</a>
                </h3>
                <!-- 二级，三级分类 -->
                <div
                  class="item-list clearfix"
                  :style="{display: currentIndex==index? 'block': 'none'}"
                >
                  <div class="subitem" v-for="(c2) in c1.categoryChild" :key="c2.categoryId">
                    <dl class="fore">
                      <dt>
                        <a
                          :data-categoryName="c2.categoryName"
                          :data-category2Id="c2.categoryId"
                        >{{ c2.categoryName }}</a>
                      </dt>
                      <dd>
                        <em v-for="(c3) in c2.categoryChild" :key="c3.categoryId">
                          <a
                            :data-categoryName="c3.categoryName"
                            :data-category3Id="c3.categoryId"
                          >{{ c3.categoryName }}</a>
                        </em>
                      </dd>
                    </dl>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </transition>
      </div>
      <nav class="nav">
        <a href="###">服装城</a>
        <a href="###">美妆馆</a>
        <a href="###">尚品汇超市</a>
        <a href="###">全球购</a>
        <a href="###">闪购</a>
        <a href="###">团购</a>
        <a href="###">有趣</a>
        <a href="###">秒杀</a>
      </nav>
    </div>
  </div>
</template>

<script>
//vuex辅助函数mapState获取仓库数据
import { mapState } from "vuex";
// 引入lodash实现节流（这里是按需引入的）
import throttle from 'lodash/throttle'


export default {
  name: "TypeNav",
  data () {
    return {
      // 存储用户鼠标移上哪一个一级分类
      currentIndex: -1,
      show: true
    }
  },

  mounted () {
    // 通知Vuex发送请求，获取数据，存储在仓库中。
    // this.$store.dispatch('getCategory');

    // 如果不是home组件就会隐藏
    if (this.$route.path != '/home') {
      this.show = false
    }
  },
  computed: {
    //mapState辅助函数中的对象右侧函数，注入的实参是vuex的大仓库的state
    ...mapState({
      categoryList: (state) => state.home.categoryList,
    }),
  },

  methods: {
    // 鼠标进入修改响应式数据currentIndex属性
    // changeIndex(index) {
    //   this.currentIndex = index
    // },
    // 节流功能的实现
    changeIndex: throttle(function (index) {
      this.currentIndex = index
    }, 50),

    resetCurrentIndex () {
      this.currentIndex = -1
    },

    goSearch (event) {
      //点击a标签进行路由跳转：父节点代理的子节点的类型很多 div h3 dd dt em a
      //通过event可以获取到当前触发事件的节点
      let nodeElement = event.target;
      //给a标签添加自定义属性data-categoryName，保证这个节点带data-categoryName，一定是a标签
      //可以通过节点的dataset属性获取相应节点的自定义属性，返回的是一个对象KV【自定义属性相关的】
      //如果带有categoryname字段的一定是a标签
      let { categoryname, category1id, category2id, category3id } =
        nodeElement.dataset;
      //执行if语句：只能区分点击的标签是不是a
      if (categoryname) {
        //准备路由跳转的参数
        let location = { name: "search" };
        let query = { categoryName: categoryname };
        //一级分类的a标签
        if (category1id) {
          query.category1Id = category1id;
          //二级分类的a标签
        } else if (category2id) {
          query.category2Id = category2id;
          //三级分类a标签
        } else {
          query.category3Id = category3id;
        }
        //路由跳转之前：看一下有没有params参数，如果有params参数需要携带给search
        if (this.$route.params) {
          //query参数
          location.query = query;
          //params
          location.params = this.$route.params;
        
          //如有有params参数也需要携带给search模块
          //home->search确实需要记录历史
          //search->search不需要存储历史记录
          if (this.$route.path != "/home") {
            this.$router.replace(location);
          } else {
            this.$router.push(location);
          }
        }
      }
    },

    enterShow () {
      if (this.$route.path != '/home') {
        this.show = true
      }
    },
    leaveShow () {
      this.currentIndex = -1
      if (this.$route.path != '/home') {
        this.show = false
      }
    }
  },

};
</script>

<style scoped lang="less">
.type-nav {
  border-bottom: 2px solid #e1251b;

  .container {
    width: 1200px;
    margin: 0 auto;
    display: flex;
    position: relative;

    .all {
      width: 210px;
      height: 45px;
      background-color: #e1251b;
      line-height: 45px;
      text-align: center;
      color: #fff;
      font-size: 14px;
      font-weight: bold;
    }

    .nav {
      a {
        height: 45px;
        margin: 0 22px;
        line-height: 45px;
        font-size: 16px;
        color: #333;
      }
    }

    .sort {
      position: absolute;
      left: 0;
      top: 45px;
      width: 210px;
      height: 461px;
      position: absolute;
      background: #fafafa;
      z-index: 999;

      .all-sort-list2 {
        .item {
          h3 {
            line-height: 27px;
            font-size: 14px;
            font-weight: 400;
            overflow: hidden;
            padding: 0 20px;
            margin: 0;

            a {
              color: #333;
              text-decoration: none;
              cursor: default;
            }
          }

          .item-list {
            display: none;
            position: absolute;
            width: 734px;
            min-height: 460px;
            background: #f7f7f7;
            left: 210px;
            border: 1px solid #ddd;
            top: 0;
            z-index: 9999 !important;

            .subitem {
              float: left;
              width: 650px;
              padding: 0 4px 0 8px;

              dl {
                border-top: 1px solid #eee;
                padding: 6px 0;
                overflow: hidden;
                zoom: 1;

                &.fore {
                  border-top: 0;
                }

                dt {
                  float: left;
                  width: 54px;
                  line-height: 22px;
                  text-align: right;
                  padding: 3px 6px 0 0;
                  font-weight: 700;
                  cursor: pointer;
                }

                dd {
                  float: left;
                  width: 415px;
                  padding: 3px 0 0;
                  overflow: hidden;

                  em {
                    float: left;
                    height: 14px;
                    line-height: 14px;
                    padding: 0 8px;
                    margin-top: 5px;
                    border-left: 1px solid #ccc;
                    cursor: pointer;
                  }
                }
              }
            }
          }

          // &:hover {
          //   .item-list {
          //     display: block;
          //   }
          // }
        }
        .cur {
          background-color: skyblue;
        }
      }
    }

    // sort的过渡动画
    // 过渡动画的开始
    .sort-enter {
      height: 0;
    }
    // 过渡动画的结束
    .sort-enter-to {
      height: 461px;
    }
    // 过渡动画的类型
    .sort-enter-active {
      transition: all 0.3s linear;
    }
  }
}
</style>

